rain or
snowstorms, swimming cold rivers; also certain general diseases like
rheumatism, arthritis, influenza, and disorders of the digestive
organs, may become complicated by this affection. From the close
relation between the brain and eye--alike in the blood vessels and
nerves--disorders of the first lead to affection of the second, and the
same remark applies to the persistent irritation to which the jaws are
subjected in the course of dentition. So potent is the last agency that
we dread a recurrence of ophthalmia so long as dentition is incomplete,
and hope for immunity if the animal completes its dentition without any
permanent structural change in the eye.

_Symptoms._--The symptoms will vary according to the cause. If the
attack is due to direct physical injury, the inflammation of the eyelids
and superficial structures may be quite as marked as that of the
interior of the eye. If, on the other hand, from general causes, or as a
complication of some distant disease, the affection may be largely
confined to the deeper structures, and the swelling, redness, and
tenderness of the superficial structures will be less marked. When the
external coats thus comparatively escape, the extreme anterior edge of
the white or sclerotic coat, where it overlaps the border of the
transparent cornea, is in a measure free from congestion, and, in the
absence of the obscuring dark pigment, forms a whitish ring around the
cornea. This is partly due to the fact that a series of arteries
(ciliary) passing to the inflamed iris penetrate the sclerotic coat a
short distance behind its anterior border, and there is therefore a
marked difference in color between the general sclerotic occupied
between these congested vessels and the anterior rim from which they are
absent. Unfortunately, the pigment is often so abundant in the anterior
part of the sclerotic as to hide this symptom. In internal ophthalmia
the opacity of the cornea may be confined to a zone around the outer
margin of the cornea, and even this may be a bluish haze rather than a
deep, fleecy white. In consequence it becomes impossible to see the
interior of the chamber for the aqueous humor and the condition of the
iris and pupil. The aqueous humor is usually turbid, and has numerous
yellowish-white flakes floating on its substance or deposited in the
lower part of the chamber, so as to cut off the view of the lower
portion of the iris. The still visible portion of the iris ha